Exam
2, Biology 301D, 16 October 2002 Printed
name (required) ________________
101
points possible
1. (4 pts.)
(2pts)
Key Code: Fill in (A) and (B) on scantron question 1. to indicate your exam code.
(2pts) Social
security number and name. Bubble in the scantron with your name and your
social security number (your SSN goes in the first 9 bubbles of the scantron ID
field).
NEW: Put your name on this hard copy, or you may not get credit
for taking the exam.
When
finished, turn in both the Scantron
and hard copy. You may write on this hard copy, but your grade will be
determined by the Scantron form, provided we can find a hard copy from you.
None, one, all, or
any combination of individual
answers may apply to a question
unless stated otherwise. We
use the acronym “NOM” for “None, One, or Many.”
As usual, phrases in italics may be taken as true.
2.
(4 pts NOM)
Which of the following points were raised about models and acrylamides?
(A)
Acrylamides
are created by cooking certain foods to high temperature (especially fries,
chips, and other carbohydrates) and are suspected of causing heart disease.
(B)
The
models that have been used to assess the risk of acrylamides includes
experiments with rats and occupational exposures to humans
(C)
On
the basis of the current models for the health effects of acrylamides, the
government has determined that the levels of acrylamides in fries and chips is
harmful to humans.
(D)
The
rat model of the harmful effects of acrylamides has given different results
than those obtained from humans, hence various scientists are wary of the
results obtained from rats.
3.
(4 pts NOM)
Which points were made about models in breast cancer?
(A)
Recent
work in molecular biology has found that there are at least 3-4 different types
of breast cancer.
(B)
The
recognition of multiple types of cancer within cancers that were formerly
lumped under one type is likely to affect diagnosis and to improve treatment of
cancers.
(C)
The
value of the current method of screening for breast cancer (mammography) has
been questioned because it yields many false positives.
4. (6 pts NOM)
Which of the following technologies, as used in US courts or used by US
government agencies, were said in class to be governed by regulations that
require most (or all) features of ideal data? If an item was not discussed in
class, do not fill it in.
(A)
hair matching (by means other than DNA)
(B)
dog sniffing matching of people and clothing
(C)
fingerprints (not DNA fingerprints, but real
fingerprints)
(D)
DNA typing
(E)
Drug testing (as implemented by the Dept. of
Transportation)
(F)
Polygraph (lie detection)
5.
(8 pts NOM) Which of the following
points were presented in class as true?
(A)
When fingerprint experts have been subjected to proficiency tests, their false
positive rates ranged from 3% to over 20%.
(B)
The large database of human fingerprints that have been maintained for years
(by the FBI) has ensured low error rates in recent fingerprint analyses.
(C)
A proficiency test is a test involving the use of standards. It establishes a human and technical error
rate.
(D)
The routine use of DNA tests in the last few years of criminal investigation
has shown that in approximately one of every four cases, the prosecution’s
first choice of a “prime” suspect did not commit the crime.
(E)
Since the death penalty was reinstated in 1976, slightly more than 1% of people
sentenced to die have been released because they were later shown to be
innocent by new evidence. Although even
this low percentage is disturbing, we have good reason to believe that this is
a relatively accurate number of the total number of innocent people convicted
to die.
(F)
A very recent report by a government committee has declared that lie detection
by polygraph (the old lie detector test) to be 98% accurate and thus supports
its continued use.
(G)
In 62 cases of convictions that were later overturned by DNA evidence,
the most common factor leading to wrongful conviction was mistaken identity.
Data: Error
6-9. (4 pts each). For each of the following
descriptions, indicate the types of error present (the italicized phrase identifies the error). Mark a type of error only
if it is definitely present. Do not assume any more than what is explicitly
mentioned in the problem. One answer and
only one for each question.
|
(A) |
(B) |
(C) |
(D) |
(E) |
Types of error: |
Rounding, Precision and accuracy |
Sampling |
Human and technical |
Bias |
No error is indicated |
6. (4 pts) Some old methods
of DNA typing involved running two samples side-by-side on the same gel (e.g.,
a suspect sample and the forensic sample), and then measuring the bar code for
each sample. In some cases it was found
that the technician reported that the two bar codes were the same when they
were really slightly different from each other. The cause of the erroneous “match” was that the technician knew
what outcome was expected and made the measurements of one bar code while also
looking at the other bar code. What
type of error is evident in the misreading of a bar code because the
measurements were not made independently?
(one answer only)
(A) (B) (C)
(D) (E)
7. (4 pts) The scantron reader often scores options
that have been erased. Thus the
scantron electronic file does not exactly match the answers on the paper
scantron form. What type of error is
indicated by the difference between the paper scantron form and the
electronic file? (one answer only)
(A) (B) (C) (D) (E)
8. (4 pts) In many classes,
teachers grade written exams and assignments knowing whose paper is being
graded at the time. It seems likely
that, for some teachers (and we will assume so), students are graded somewhat unfairly
whenever the teacher has already developed a sense of each student’s quality,
because the teacher then assumes that good students know what they are writing
about but that poor students don’t. In
other words, the teacher would assign a higher score to the “good” student than
to the “bad” student for the same piece of work. This problem would be avoided if the teacher was unaware of whose
paper was being graded. What type of
error is indicated by the unfair scores? (one answer only)
(A) (B) (C)
(D) (E)
9. (4 pts) Clinical trials
with vaccines or drugs are limited to a few thousand individuals. A drug/vaccine that shows no complications
in a clinical trial may nonetheless cause complications when it is used by
millions (the rate of complications in the general population might be one per
few-thousand people). What type of
error is indicated by the lack of even a single complication in the clinical
trial but the observance of complications when the drug is released to the
public? (one answer only)
(A) (B) (C)
(D) (E)
10. (6 pts NOM) In which of the following descriptions is a
blind procedure present as pertains to the goal? Do not assume more than the problem describes. Fill in all options that describe a blind
procedure or for which the answer is “yes.”
If the status of blind cannot be determined from the description, do not
select that option.
(A)
The goal is to determine human and technical
error rates through replication of individual samples. Samples are coded before being sent for
testing, and tubes containing the same sample have the same code.
(B)
Numbers are drawn from a hat to determine who is
tested for drugs this month. Samples
are taken from the chosen individuals and sent to the lab. Is the testing done blindly?
(C)
For written (typed) assignments, students draw a
number at random. They put that number
as the only identifier on the assignment, and once it is graded, the students
indicate which number belongs to them.
Is the grading done blindly?
(D)
A person reads their horoscope for the previous
month and decides that most of what was supposed to happen did happen. Is the reading done blindly?
(E)
Gregor Mendel (of genetics fame) crossed
different pea plants and measured characteristics of both the parents and
offspring to study inheritance. He
carefully kept track of which parents were used and which offspring were
obtained from each cross, and he measured the offspring separately for each set
of parents. Were his measurements of
offspring done blindly?
(11-15). (4 pts each) For each of the following statements, mark the letters corresponding to the appropriate design features. Base your answer only on the information given. That is, mark a data feature only if it is explicitly present in the problem description. Use only the options given in class or the book (At least one bubble, but possibly many bubbles = One or Many).
(A) explicit protocol |
(C) standards |
(E) blind |
(B) replicates |
(D) random |
(F) None |
11. (4 pts OM). Which features were identified as important
in reducing bias?
(A) (B) (C) (D) (E) (F)
12. (4 pts OM). Which features were identified as important
in reducing sampling error?
(A) (B) (C) (D) (E) (F)
13. (4 pts OM) The prosecution
in a court case calls an expert witness to defend a new method of lie
detection, based on brain waves measured when the person is asked
questions. This expert testifies that
his method has been tested on 500 undergraduates who either deliberately told
lies or told the truth about questions they were asked. The design for the study had been submitted to
the National Science Foundation and had been funded for $250,000 before it was
carried out. Students were assigned to “truth” and “lie” groups based on which
class in which they were registered, but even so, the person doing the analysis
of brain waves was not aware of which students had been told to lie or tell the
truth. The expert witness said that the
method had been able to correctly classify all truth-tellers and liars in the
study.
(A) (B) (C) (D) (E) (F)
14. (4 pts OM) A farmer wants
to know if using pesticide will increase the amount of wheat harvested. To test
this hypothesis, he applies the pesticide to each plot in his field that shows
heavy pest infestation.. At the end of summer, the yield of wheat is compared
between treated and untreated plots.
However, since all heavily-infested areas were treated and no
lightly-infested area was treated, he finds himself in the unfortunate
situation of not knowing whether the pesticide improved the crop yield.
(A) (B) (C) (D) (E) (F)
15. (4 pts OM) A teacher wants
to know if students learn more early in the morning than late in the
morning. So she teaches two sections of
the same class, one at 08:00 and one at 11:00.
Only 50 students sign up for the 08:00 class, but 100 sign up for the
11:00 class. She attempts to give the
same lecture at both times, but finds that the second lecture is usually better
because she has practiced it already that day.
However, she doesn’t bother to tell the students about her experiment,
and as a consequence, many of the 08:00 students come to lecture at 11:00. In the end, she is not able to reach a firm
conclusion about learning and the time of day.
(A) (B) (C) (D) (E) (F)
(16-18)
(3 pts
each). Do-it-yourself protocol. You are conducting an external review/test of a
DNA lab. Your job is to send two tubes to the lab, with labels. There
are several options for the content of and label on a tube. You must decide
which contents to send and how to label the tubes so that the features of ideal
data requested in the question are present from the lab's perspective. If a
tube has a person's name on it, the lab can assume that the tube contents
belong to the name of the person on the label. If a tube is labeled with a
number, the contents are unknown to the lab but known to you. Your options for
tube contents and tube labels are:
option |
tube label |
Contents in the tube are from |
ABO Blood type
|
Rh blood type |
Gender |
(A) |
Sam
Edwards |
Sam
Edwards |
AB |
+ |
Male |
(B) |
Chuck
Berry |
Chuck
Berry |
O |
- |
Male |
(C) |
Marty Ray |
Marty Ray |
O |
+ |
Male |
(D) |
#13 |
Wanda
Crill |
A |
- |
Female |
(E) |
#21 |
John
Crill |
A |
+ |
Male |
(F) |
June
Scott |
June
Scott |
B |
+ |
Female |
(G) |
#101 |
June
Scott |
B |
+ |
Female |
(H) |
#243 |
Linda
Davis |
O |
- |
Female |
(I) |
#17 |
Joel
Sachs |
AB |
+ |
Male |
(J) |
No
combination of tubes can satisfy the protocol |
In
the following questions, choose two letters among options (A)-(I) to describe
the two tubes that will be sent to the lab. If it is possible to satisfy the protocol, the question will require
exactly two letters and only
two letters -- one for each tube. Thus, the answer for a question might be
(A) & (B), or it might be (D) & (F). If more than one pair of options
are possible correct answers, fill in only one correct pair of options. Thus,
if (A) & (B) is one acceptable answer, and (C) & (D) is another acceptable
answer, fill in either (A)&(B) or
(C)&(D), but not both. If a factor
(such as identity, blood type, gender) is not specified in the protocol, then
that factor will be ignored in grading the answer. Alternatively, if a
protocol cannot be satisfied with the options for tubes (A)-(I), fill in (J).
16. (3 pts) Choose two tubes
to guarantee replication of ABO and Rh blood type without replication of
person.
two tubes: (A) (B) (C) (D) (E) (F) (G) (H) (I) (J)
17.
(3 pts) The lab has a way to identify the gender (sex) of a sample. Make the
protocol fully blind to the lab and replicated for gender but not replicated
for an individual or for either blood type.
two tubes: (A) (B) (C) (D) (E) (F) (G) (H) (I) (J)
18.
(3 pts) Make the protocol fully blind to the lab and not replicated in any way
(not for gender, either blood type, nor individual).
two tubes: (A) (B) (C) (D) (E) (F) (G) (H) (I) (J)
19. (4 pts NOM).
Which of the following are true?
(A)
A study can be randomized in some respects but not
others.
(B)
A study can be blind in some ways but not others.
(C)
A study can be replicated in some ways but not
others.
(D)
A study can completely lack blind features,
randomization, and standards.
(E)
No study can be replicated in all respects.
(20,
21). (4 pts
each) Each of items (A) through (G)
describes a feature of Department of Transportation drug tests. The details of the drug testing rules are
presented in the Federal Register 49 CFR PART 40 and described in a 100+ page
pamphlet "Guidelines for Implementing the FHWA anti-drug program."
(A) Each manager whose employees are tested is
required to include 3 known blank samples (lacking drugs) for every 100
unknowns; managers with more than 2000 drivers must also include some samples
known to contain drugs.
(B) The laboratory initially tests all samples
with a rapid screen; positive samples are retested more comprehensively.
(C) When a sample is sent to the laboratory for
testing, it is labeled with a code, rather than the name of the person being
tested.
(D) Split sample collection is required -- the
partitioning of the original sample into two vials -- so that the second sample
can be retained for retesting.
(E) The rules specify that any retesting (in the
event of a positive sample) is to be done by a different laboratory than did
the original test.
(F) The regulations require that any driver
involved in an accident be tested for drugs and alcohol.
(G) Lab results are sent to the medical review
officer before being returned to the office originating the test.
20. (4 pts) Which feature(s)
represent standards in some part of the drug-testing protocol, even when
retesting is not done? (none, one, or many)
(A) (B) (C) (D) (E) (F) (G)
21. (4 pts) Which feature(s),
if followed, ensure that DOT drug tests of an individual's sample are done
blind? (none, one, or many)
(A) (B) (C) (D) (E) (F) (G)
DNA Typing
22. (4 pts) It
was suggested in class that lab error rates from such problems as sample mixup
are still on the order of 1% in modern DNA typing. Consider a trial in which the lab has declared a match, with a
random match probability of 1/billion; but it is also known that the lab makes
a mistake 1% of the time in declaring a match.
How should the jury’s calculation of the significance of the match be
affected by the lab error rate? (NOM)
(A) The lab error rate does not affect the calculation,
because by the time the data are presented at trial, lab errors have been
corrected.
(B) The lab error rate does not affect the calculation,
because the random match probability has already taken lab error into account.
(C) The lab error rate affects the calculation in a
minor way. The proper correction is to
multiply the probability that no lab error occurred (which is 0.99) times the
random match probability (1/billion) to get the corrected value, which is still
nearly 1/billion.
(D) The lab error rate affects the calculation in a
major way. There is a 1% chance that
the sample did not come from the suspect because of lab error, plus a 1/billion
chance that the sample did not come from the suspect because of a random match
to someone else. Overall, there is
approximately a 1% chance that the sample did not come from the suspect – the
calculation is dominated by the lab error rate.
23. (4 pts NOM).
Which exceptions to ideal data were evident in the DNA analysis of the
Castro Case (as per the book)?
(A)
lack of blind analysis
(B)
lack of standards
(C)
lack of randomization
(D)
lack of replication
(E)
Violation of protocol
24.(4 points NOM)
Which facts about modern DNA typing are true?
(A)
When done properly, DNA results have a low
probability of producing a chance or random match between the forensic sample
and a person not associated with the crime.
This probability is often less than 1/million.
(B)
DNA typing can be performed from most tissues and
needs only trace amounts of tissue. For
example, enough DNA can be recovered from the back of a postage stamp or a
baseball bat handle to determine whether a particular suspect licked the stamp
or held the bat.
(C)
The use of
PCR (“Xeroxing” DNA) has allowed tests on small forensic samples of DNA to be
replicated many times.
(D)
Current lab errors are largely caused by problems
with DNA typing machines and are likely to become much less common as better
equipment is developed.